Ronja is a DIY project of optical wireless datalink hardware. Karel Kulhavy of Twibright Labs, creator of the project, held a talk about Ronja on WSFII (World Summits on Free Information Infrastructures) in London in 2005. This is the complete recording of the talk, cleaned up (ummmm....ummmm.... edited out, otherwise unabridged)
The audio is released under GNU FDL (GFDL) licence. The field is displaying Attribution-ShareAlike 2.5 because there was no option to select GFDL directly.